1. Field of the Invention
The present invention is directed to a device for shaping an electrode cable, such as a medical electrode cable of the type employed with a pacemaker.
2. Description of the Prior Art
The use of J-shaped electrode cables for supporting the electrode tip, used for stimulating the atrial appendage of a patient, and designed to press against the wall of the atrial appendage has long been known. One such electrode device is disclosed in U.S. Pat. No. 4,402,328. Because of the precurved shape of the electrode cable, the electrode head remains in place against the atrial appendage wall, and tends to remain in that position. Another means for shaping an electrode cable is described in U.S. Pat. No. 4,136,703. A relatively stiff tube extending the length of the electrode cable is inserted into the stylet channel of the electrode cable. A J-shaped, precurved stylet is introduced into the tube and is maintained straight by the tube. When the distal end of the electrode cable is inside the heart, the tube is retracted, thereby exposing the stylet which then shapes the distal end of the cable. A disadvantage of this known electrode cable is that it is extremely stiff. If the stylet is removed from the electrode cable, the electrode tip positioned in the atrial appendage would attempt to pull itself out of position, because of the weight of the electrode cable.
A combined electrode and catheter are disclosed in U.S. Pat. No. 3,890,977 having portions thereof consisting of a so-called "shape memory" metal. The shape memory metal components are disposed at specific locations along the electrode-catheter cable. After the cable has been implanted in the heart of a patient, the cable is shaped by the shape memory components assuming a predetermined shape, upon being elevated to a body temperature.
A disadvantage shared by all of the above-described known electrode devices is that they require a large assortment of J-shaped electrode cables and/or precurved stylets of different sizes, because the difference between the bend in the cable and the electrode tip must be adapted, to greater or lesser degrees, to the size of each patient's heart.